Alzheimer disease

Voluntary Running Attenuates Memory Loss, Decreases Neuropathological Changes and Induces Neurogenesis in a Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by loss of memory and cognitive abilities, and the appearance of amyloid plaques composed of the amyloid-β peptide (Aβ) and neurofibrillary tangles formed of tau protein. It has been suggested that exercise might ameliorate the disease; here, we evaluated the effect of voluntary running on several aspects of AD including amyloid deposition, tau phosphorylation, inflammatory reaction, neurogenesis and spatial memory in the double transgenic APPswe/PS1ΔE9 mouse model of AD. We report that voluntary wheel running for 10 weeks decreased Aβ burden, Thioflavin-S-positive plaques and Aβ oligomers in the hippocampus. In addition, runner APPswe/PS1ΔE9 mice showed fewer phosphorylated tau protein and decreased astrogliosis evidenced by lower staining of GFAP. Further, runner APPswe/PS1ΔE9 mice showed increased number of neurons in the hippocampus and exhibited increased cell proliferation and generation of cells positive for the immature neuronal protein doublecortin, indicating that running increased neurogenesis. Finally, runner APPswe/PS1ΔE9 mice showed improved spatial memory performance in the Morris water maze. Altogether, our findings indicate that in APPswe/PS1ΔE9 mice, voluntary running reduced all the neuropathological hallmarks of AD studied, reduced neuronal loss, increased hippocampal neurogenesis and reduced spatial memory loss. These findings support that voluntary exercise might have therapeutic value on AD.

What is your patient's cognitive profile? Three distinct subgroups of cognitive function in persons with heart failure

PURPOSE

The aim of this study was to determine whether patients with heart failure (HF) have distinct profiles of cognitive impairment.

BACKGROUND

Cognitive impairment is common in HF. Recent work found three cognitive profiles in HF patients-(1) intact, (2) impaired, and (3) memory-impaired. We examined the reproducibility of these profiles and clarified mechanisms.

METHODS

HF patients (68.6 ± 9.7 years; N=329) completed neuropsychological testing. Composite scores were created for cognitive domains and used to identify clusters via agglomerative-hierarchical cluster analysis.

RESULTS

A 3-cluster solution emerged. Cluster 1 (n=109) had intact cognition. Cluster 2 (n=123) was impaired across all domains. Cluster 3 (n=97) had impaired memory only. Clusters differed in age, race, education, SES, IQ, BMI, and diabetes (ps ≤ .026) but not in mood, anxiety, cardiovascular, or pulmonary disease (ps ≥ .118).

CONCLUSIONS

We replicated three distinct patterns of cognitive function in persons with HF. These profiles may help providers offer tailored care to patients with different cognitive and clinical needs.

The Mechanism of Memory Enhancement of Acteoside (Verbascoside) in the Senescent Mouse Model Induced by a Combination of D-gal and AlCl3

Acteoside (verbsacoside), one of the main active phenylethanoid glycosides from Cistanche deserticola, is known to have antioxidant and neuroprotective activity, and herbs containing it are used to enhance memory. However, there is relatively little direct experimental evidence to support the use of acteoside in Alzheimer's disease (AD). The purpose of this study was to elucidate the effects of acteoside in improving learning and memory, using a mouse model of senescence induced by a combination of d-galactose and AlCl3 , and investigate its potential mechanisms compared with the positive controls vitamin E and piracetam. Acteoside was administered intragastrically at doses of 30, 60 and 120 mg/kg/day for 30 days after AD was induced. Memory function was evaluated using a step-down test. The number of neuron was analysed by haematoxylin and eosin staining and the number of Nissl bodies by Nissl staining. The expression of caspase-3 protein in hippocampus was detected by immunohistochemistry and western blot. Nitric oxide and total nitric oxide synthase level in hippocampus were also assessed. Our results showed that the latency of step down was shortened in AD model mice and the number of errors decreased after treatment with all doses of acteoside. Neurons and Nissl bodies in the hippocampus were increased significantly with higher doses (60 and 120 mg/kg/day) of acteoside. The content of nitric oxide, the activity of nitric oxide synthase and the expression of caspase-3 protein were decreased by 120 mg/kg/day acteoside compared with that of the AD model group. Our results support the results obtained previously using the Morris maze test in the same mouse model of senescence, and the use of traditional medicinal herbs containing acteoside for neuroprotection and memory loss.

ATP leakage induces P2XR activation and contributes to acute synaptic excitotoxicity induced by soluble oligomers of β-amyloid peptide in hippocampal neurons

Recent studies suggest that the toxic effects of Aβ can be attributed to its capability to insert in membranes and form pore-like structures, which are permeable to cations and molecules such as ATP. Our working hypothesis is that Aβ increases extracellular ATP causing activation of P2X receptors and potentiating excitatory synaptic activity. We found that soluble oligomers of β-amyloid peptide increased cytosolic Ca(2+) 4-fold above control (415 ± 28% of control). Also, ATP leakage (157 ± 10% of control) was independent of extracellular Ca(2+), suggesting that ATP traveled from the cytosol through an Aβ pore-mediated efflux and not from exocytotic mechanisms. The subsequent activation of P2XR by ATP can contribute to the cytosolic Ca(2+) increase observed with Aβ. Additionally, we found that β-amyloid oligomers bind preferentially to excitatory neurons inducing an increase in excitatory synaptic current frequency (248.1 ± 32.7%) that was blocked by the use of P2XR antagonists such as PPADS (Aβ + PPADS: 110.9 ± 18.35%) or Apyrase plus DPCPX (Aβ + inhibitors: 98.97 ± 17.4%). Taken together, we suggest that Aβ induces excitotoxicity by binding preferentially to excitatory neuron membranes forming a non-selective pore and by increasing intracellular calcium by itself and through P2XR activation by extracellular ATP leading to an augmention in mEPSC activity. All these effects were blocked with a non-specific P2XR antagonist, indicating that part of the neurotoxicity of Aβ is mediated by P2XR activation and facilitation of excitatory neurotransmitter release. These findings suggest that P2XR can be considered as a potential new target for the development of drugs or pharmacological tools to treat Alzheimer's disease. This article is part of the Special Issue entitled 'Synaptopathy--from Biology to Therapy'.

Flavonoid-based therapies in the early management of neurodegenerative diseases

During the past several years, there has been enormous progress in the understanding of the causative factors that initiate neuronal damage in various neurodegenerative diseases, including Alzheimer disease, Parkinson disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington disease. Preventing neuronal damage and neuronal death will have a huge clinical benefit. However, despite major advances in causative factors that trigger these neurodegenerative diseases, to date there have been no therapies available that benefit patients who suffer from these diseases. Because most neurodegenerative diseases are late-onset and remain asymptomatic for most of the phases, the therapies initiated in advanced stages of the disease have limited value to patients. It may be possible to prevent or halt the disease progression to a great extent if therapies start at the initial stage of the disease. Such therapies may restore neuronal function by reducing or even eliminating the primary stressor. Flavonoids are key compounds for the development of a new generation of therapeutic agents that are clinically effective in treating neurodegenerative diseases. Regular consumption of flavonoids has been associated with a reduced risk of neurodegenerative diseases. In addition to their antioxidant properties, these polyphenolic compounds exhibit neuroprotective properties by their interaction with cellular signaling pathways followed by transcription and translation that mediate cell function under both normal and pathologic conditions. This review focuses on human intervention studies as well as animal studies on the role of various flavonoids in the prevention of neurodegenerative diseases.

The role of copper ions in pathophysiology and fluorescent sensors for the detection thereof

Copper ions are crucial to life, and some fundamental roles of copper in pathophysiology have been elucidated using fluorescent sensors.

Resolution of inflammation is altered in Alzheimer's disease

BACKGROUND

Resolution is the final stage of the inflammatory response, when restoration of tissue occurs. Failure may lead to chronic inflammation, which is known as part of the pathology in the brain of individuals with Alzheimer's disease (AD).

METHODS

Specialized pro-resolving mediators (SPMs), receptors, biosynthetic enzyme, and downstream effectors involved in resolution were analyzed in postmortem hippocampal tissue from AD patients and non-AD subjects. SPMs were analyzed in cerebrospinal fluid (CSF).

RESULTS

SPMs and SPM receptors were detected in the human brain. Levels of the SPM lipoxin A4 (LXA4) were reduced in AD, both in the CSF and hippocampus. An enzyme involved in LXA4 synthesis and two SPM receptors were elevated in AD brains. LXA4 and RvD1 levels in CSF correlated with Mini-Mental State Examination (MMSE) scores.

CONCLUSIONS

A resolution pathway exists in the brain and the alterations described herein strongly suggest a dysfunction of this pathway in AD. MMSE correlations suggest a connection with cognitive function in AD.

Association Study of the TREM2 Gene and Identification of a Novel Variant in Exon 2 in Iranian Patients with Late-Onset Alzheimer's Disease

OBJECTIVE

To analyze the association between TREM2 exon 2 variants and late-onset (sporadic) Alzheimer's disease (AD) in an elderly Iranian population.

MATERIALS AND METHODS

Exon 2 of TREM2 in a total of 131 AD patients and 157 controls was genotyped using polymerase chain reaction and Sanger sequencing. Fisher's exact test was used to compare the allele and genotype frequency between the 2 study groups.

RESULTS

One homozygous and 2 heterozygous carriers of rs75932628-T in the AD patients and 1 heterozygous carrier in the control group were identified. One novel damaging variant, G55R, was also detected in the AD patient group. The frequency of rs75932628-T as well as the amount of rare variants were higher in the AD patients than in the controls, but this did not reach a statistically significant association with AD (odds ratio: 4.8; 95% confidence interval: 0.54 to 43.6; p = 0.270).

CONCLUSION

The rs75932628-T allele frequency in the elderly Iranian population (0.86%) was high.

Purine homo-N-nucleoside+coumarin hybrids as pleiotropic agents for the potential treatment of Alzheimer's disease

AIM

Due to the complex nature of Alzheimer's disease, there is a renewed search for pleiotropic agents.

RESULTS

Purine+coumarin hybrids have been synthesized and tested for the potential treatment of Alzheimer's disease. Hybrids 6, 4a-b, 14c and 14e inhibit significantly soybean lipoxygenase, whereas derivatives 14b, c and 20a present antioxidative/lipoxygenase inhibition activities. Cholinesterase (ChE) and monoamino oxidase (MAO) inhibition studies have been carried out. Hybrid 20a is the most potent ChE inhibitor, in the low micromolar range, and selective for hBuChE (IC50 = 4.65 ± 0.23 μM), whereas hybrid 14a is the most potent MAOI, in the low micromolar range, and selective for MAO-B (IC50 = 6.8 ± 0.6 μM).

CONCLUSION

The preliminary experimental results point to two selective multitarget lead compounds 20a and 4b.

Anatomical region differences and age-related changes in copper, zinc, and manganese levels in the human brain

Using inductively coupled plasma-mass spectrometry after samples microwave-assisted acid digestion, zinc (Zn), copper (Cu), and manganese (Mn) levels were measured in 14 different areas of the human brain of adult individuals (n = 42; 71 ± 12, range 50-101 years old) without a known history of neurodegenerative, neurological, or psychiatric disorder. The main goals of the work were to establish the "normal" (reference) values for those elements in the human brain and to evaluate the age-related changes, a prior and indispensable step in order to enlighten the role of trace element (TE) in human brain physiology and their involvement in aging and neurodegenerative processes. Considering the mean values for the 14 regions, Zn (mean ± sd; range 53 ± 5; 43-61 μg/g) was found at higher levels, followed by Cu (22 ± 5; 10-37 μg/g) and Mn (1.3 ± 0.3; 0.5-2.7 μg/g). The TE distribution across the brain tissue showed to be quite heterogeneous: the highest levels of Zn were found in the hippocampus (70 ± 10; 49-95 μg/g) and superior temporal gyrus (68 ± 10; 44-88 μg/g) and the lowest in the pons (33 ± 8; 19-51 μg/g); the highest levels of Cu and Mn were found in the putamen (36 ± 13; 21-76 μg/g and 2.5 ± 0.8; 0.7-4.5 μg/g, respectively) and the lowest in the medulla (11 ± 6; 2-30 μg/g and 0.8 ± 0.3; 0.2-1.8 μg/g, respectively). A tendency for an age-related increase in Zn and Mn levels was observed in most brain regions while Cu levels showed to be negatively correlated with age.

Hydrogen sulfide: a neuromodulator and neuroprotectant in the central nervous system

Hydrogen sulfide (H2S) used to be known as a toxic gas. However, in the last two decades, accumulating evidence has revealed its role as a bioactive molecule in the biological systems. H2S has relatively high expression in the brain, exerting multiple functions in both health and diseases. It modulates neurotransmission by influencing behaviors of NMDA receptors and second messenger systems including intracellular Ca(2+) concentration and intracellular cAMP levels and so forth. H2S shows potential therapeutic value in several CNS diseases including Alzheimer's disease, Parkinson's disease, ischemic stroke, and traumatic brain injury. As a neuroprotectant, H2S produces antioxidant, anti-inflammatory, and antiapoptotic effects in pathological situations. Sulfhydration of target proteins is an important mechanism underlying these effects. This Review summarizes the current understanding of H2S in the central nervous system, with emphasis on its role as a neuromodulator and a neuroprotectant.

Maternal immune activation and abnormal brain development across CNS disorders

Epidemiological studies have shown a clear association between maternal infection and schizophrenia or autism in the progeny. Animal models have revealed maternal immune activation (mIA) to be a profound risk factor for neurochemical and behavioural abnormalities in the offspring. Microglial priming has been proposed as a major consequence of mIA, and represents a critical link in a causal chain that leads to the wide spectrum of neuronal dysfunctions and behavioural phenotypes observed in the juvenile, adult or aged offspring. Such diversity of phenotypic outcomes in the mIA model are mirrored by recent clinical evidence suggesting that infectious exposure during pregnancy is also associated with epilepsy and, to a lesser extent, cerebral palsy in children. Preclinical research also suggests that mIA might precipitate the development of Alzheimer and Parkinson diseases. Here, we summarize and critically review the emerging evidence that mIA is a shared environmental risk factor across CNS disorders that varies as a function of interactions between genetic and additional environmental factors. We also review ongoing clinical trials targeting immune pathways affected by mIA that may play a part in disease manifestation. In addition, future directions and outstanding questions are discussed, including potential symptomatic, disease-modifying and preventive treatment strategies.

Back propagation artificial neural network for community Alzheimer's disease screening in China

Alzheimer's disease patients diagnosed with the Chinese Classification of Mental Disorders diagnostic criteria were selected from the community through on-site sampling. Levels of macro and trace elements were measured in blood samples using an atomic absorption method, and neurotransmitters were measured using a radioimmunoassay method. SPSS 13.0 was used to establish a database, and a back propagation artificial neural network for Alzheimer's disease prediction was simulated using Clementine 12.0 software. With scores of activities of daily living, creatinine, 5-hydroxytryptamine, age, dopamine and aluminum as input variables, the results revealed that the area under the curve in our back propagation artificial neural network was 0.929 (95% confidence interval: 0.868-0.968), sensitivity was 90.00%, specificity was 95.00%, and accuracy was 92.50%. The findings indicated that the results of back propagation artificial neural network established based on the above six variables were satisfactory for screening and diagnosis of Alzheimer's disease in patients selected from the community.

DNA methyltransferase haplotype is associated with Alzheimer's disease

Epigenetic mechanisms have been implicated in syndromes associated with neuropsychiatric disorders, but little is known about the role of epigenetics in Alzheimer's disease (AD). DNA methylation, one of the main epigenetic mechanisms, is a complex process carried out by specific enzymes, such as DNMT1 and DNMT3B. This study aimed to investigate the association between DNMT1 and DNMT3B polymorphisms and AD. Two hundred and ten elderly subjects (108 healthy controls and 102 with AD-NINCDS/ARDA, DSM-IV-TR criteria) were assessed. DNA was obtained from whole blood, and genotypes were detected by an allelic discrimination assay using TaqMan(®) MGB probes on a real-time PCR system. The polymorphisms studied were rs2162560, rs759920 (DNMT1) and rs998382, rs2424913, rs2424932 (DNMT3B). For both genes, the polymorphisms were in strong linkage disequilibrium. Carriers of the DNMT3B TGG haplotype were associated with AD (OR=3.03, 95% CI 1.63 to 5.63, P<0.001). No significant difference between AD and the control group were observed for DNMT1 polymorphisms. This study is one of the first describing a significant association between DNMT3B polymorphisms and AD. This enzyme, which is responsible for methylation in a general way, may be involved in AD.

Wnt signaling in the nervous system and in Alzheimer's disease

Wnts comprise a large family of proteins that have shown to be part of a signaling cascade that regulates several aspects of development including organogenesis, midbrain development as well as stem cell proliferation. Wnt signaling pathway plays different roles in the development of neuronal circuits and also in the adult brain, where it regulates synaptic transmission and plasticity. It has been also implicated in various diseases including cancer and neurodegenerative diseases, reflecting its relevance in fundamental biological processes. This review summarizes the progress about Wnts function in mature nervous system with a focus on Alzheimer's disease (AD). We discuss the prospects of modulating canonical and non-canonical Wnt signaling as a strategy for neuroprotection. This will include the potential of Wnts to: (i) act as potent regulators of hippocampal synapses and impact in learning and memory; (ii) regulate adult neurogenesis; and finally (iii) control AD pathogenesis.

Association of UBQ-8i polymorphism with Alzheimer's disease in Caucasians: a meta-analysis

BACKGROUND

Several studies have reported an association between the UBQ-8i (rs12344615) polymorphism of the UBQLN1 gene and risk of Alzheimer's disease (AD), but these findings remain controversial. In this study, a meta-analysis was carried out to investigate the relationship between UBQ-8i polymorphism and AD risk and a possible synergy with apolipoprotein E (APOE)ε4 gene status.

METHODS

Case-control studies were selected from PubMed, Medline and Embase (Ovid) databases. The potential association was evaluated by odds ratios (ORs) with 95% confidence intervals (CIs). Data were analyzed with Stata version 11.0.

RESULTS

A total of 4679 AD cases and 9928 controls were included in the study. There was no evidence of heterogeneity between studies or publication bias in the meta-analysis. There were no significant differences among the examined genetic models. In the analysis stratified by age of onset, a significant association was detected in the late onset AD group under the allele (OR = 1.12, 95% CI: 1.01-1.24), heterozygote (OR = 1.15, 95% CI: 1.02-1.30) and dominant (OR = 1.13, 95% CI: 1.00-1-26) models. However, UBQ-8i polymorphism was not associated with a higher risk for AD among APOEε4 carriers.

CONCLUSION

The results suggest that UBQ-8i polymorphism may contribute to AD susceptibility, but does not synergize with APOEε4 status to increase AD risk.

Is Alzheimer's disease related to metabolic syndrome? A Wnt signaling conundrum

Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 36 million people worldwide. AD is characterized by a progressive loss of cognitive functions. For years, it has been thought that age is the main risk factor for AD. Recent studies suggest that life style factors, including nutritional behaviors, play a critical role in the onset of dementia. Evidence about the relationship between nutritional behavior and AD includes the role of conditions such as obesity, hypertension, dyslipidemia and elevated glucose levels. The coexistence of some of these cardio-metabolic risk factors is generally known as metabolic syndrome (MS). Some clinical studies support the role of MS in the onset of AD. However, the cross-talk between the molecular signaling implicated in these disorders is unknown. In the present review, we focus on the molecular correlates that support the relationship between MS and the onset of AD. We also discuss relevant issues such as the role of leptin, insulin and renin-angiotensin signaling in the brain and the possible role of Wnt signaling in both MS and AD. We discuss the evidence supporting the use of ob/ob mice, high-fructose diets, aortic coarctation-induced hypertension and Octodon degus, which spontaneously develops β-amyloid deposits and metabolic derangements, as suitable animal models to address the relationships between MS and AD. Finally, we examine emergent data supporting the role of Wnt signaling in the modulation of AD and MS, implicating this pathway as a therapeutic target in both conditions.

A proteomic approach for the involvement of the GAPDH in Alzheimer disease in the blood of Moroccan FAD cases

Several articles have highlighted the potential involvement of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in neurodegeneration by showing a non-glycolytic activity of GAPDH specifically in the brains of subjects with Alzheimer's disease (AD). The novel aim of this study was to elucidate the critical role of GAPDH and its interaction with β-amyloid in the blood of Moroccan patients with familial AD (FAD) carrying presenilin mutations and in sporadic late onset AD (LOAD). Our results show a significant decrease in the activity of GAPDH in blood samples from patients with FAD as compared to sporadic cases and healthy controls. The expression level of GAPDH in brain specimens from mutant tau transgenic mice and patients with FAD was unchanged as compared to healthy controls. In contrast, the expression level of GAPDH in blood samples from mutant tau transgenic mice and patients with FAD was decreased as compared to sporadic cases and healthy controls. Moreover, there is an accumulation of β-amyloid aggregates in the blood samples of patients with FAD and an increase in amyloid fibrils in both the blood and brain samples of these patients. Our study adds new insight to previous ones by showing the involvement of GAPDH in AD, which may influence the pathogenesis of this neurodegenerative disease.

Icariin, a phosphodiesterase-5 inhibitor, improves learning and memory in APP/PS1 transgenic mice by stimulation of NO/cGMP signalling

Phosphodiesterase-5 (PDE5) inhibitors are predominantly used in the treatment of erectile dysfunction, and have been recently shown to have a potential therapeutic effect for the treatment of Alzheimer's disease (AD) through stimulation of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signalling by elevating cGMP, which is a secondary messenger involved in processes of neuroplasticity. In the present study, the effects of a PDE5 inhibitor, icarrin (ICA), on learning and memory as well as the pathological features in APP/PS1 transgenic AD mice were investigated. Ten-month-old APP/PS1 transgenic mice overexpressing human amyloid precursor protein (APP695swe) and presenilin 1 (PS1-dE9) were given ICA (30 and 60 mg/kg) or sildenafil (SIL) (2 mg/kg), age-matched wild-type (WT) mice were given ICA (60 mg/kg), and APP/PS1 and WT control groups were given an isovolumic vehicle orally twice a day for four months. Results demonstrated that ICA treatments significantly improved learning and memory of APP/PS1 transgenic mice in Y-maze tasks. The amyloid precursor protein (APP), amyloid-beta (Aβ1-40/42) and PDE5 mRNA and/or protein levels were increased in the hippocampus and cortex of APP/PS1 mice, and ICA treatments decreased these physiopathological changes. Furthermore, ICA-treated mice showed an increased expression of three nitric oxide synthase (NOS) isoforms at both mRNA and protein levels, together with increased NO and cGMP levels in the hippocampus and cortex of mice. These findings demonstrate that ICA improves learning and memory functions in APP/PS1 transgenic mice possibly through the stimulation of NO/cGMP signalling and co-ordinated induction of NOS isoforms.

Rare Variants and Transcriptomics in Alzheimer disease

Alzheimer disease (AD) is the most common dementia in the elderly, still without effective treatment. Early-onset AD (EOAD) is caused by mutations in the genes APP, PSEN1 and PSEN2. Genome-wide association studies have identified >20 late-onset AD (LOAD) susceptibility genes with common variants of small risk, with the exception of APOE. We review rare susceptibility variants in LOAD with larger effects that have been recently identified in the EOAD gene APP and the newly discovered AD genes TREM2 and PLD3. Human genetic studies now consistently support the amyloid hypothesis of AD for both EOAD and LOAD. Moreover, they identified biological processes that overlap with human transcriptomics studies in AD across different tissues, such as inflammation, cytoskeletal organization, synaptic functions, etc. Transcriptomic profiles of pre-symptomatic AD-associated variant carriers already reflect specific molecular mechanisms reminiscent to those of AD patients. This might provide an avenue for personalized medicine.

Picralima nitida seeds suppress PGE2 production by interfering with multiple signalling pathways in IL-1β-stimulated SK-N-SH neuronal cells

ETHNOPHARMACOLOGICAL RELEVANCE

The dried seed of Picralima nitida is used in rheumatic fever and as an antipyretic in West Africa. In this study we have investigated the effects of an extract obtained from the seeds of Picralima nitida (PNE) on PGE2 production in IL-1β-stimulated cells.

MATERIALS AND METHODS

Prostaglandin E2 (PGE2) was measured in supernatants of IL-1β-stimulated SK-N-SH cells using enzyme immunoassay (EIA) for PGE2. In Cell ELISA and western blot were used to evaluate the effects of PNE on protein expressions of COX-2, mPGES-1, IκB and IKK. To determine the effect of the extract on NF-κB transactivation, a reporter gene assay was carried out in HEK293 cells stimulated with TNFα. An ELISA was used to measure the roles of p38, ERK1/2 and JNK Mitogen Activated Protein Kinases (MAPKs) on anti-neuroinflammatory actions of PNE.

RESULTS

Results show that PNE significantly inhibited PGE2 production, as well as COX-2 and mPGES-1 protein expressions in IL-1β-stimulated SK-N-SH cells. Molecular targeting experiments showed that PNE interfered with NF-κB signalling pathway through attenuation of TNFα-stimulated NF-κB transcriptional activation in HEK 293 cells. Furthermore, IL-1β-mediated phosphorylation of IκB and IKK were inhibited in SK-N-SH cells. PNE (50-200 μg/ml) also produced significant inhibition of IL-1β-induced p38 MAPK phosphorylation in SK-N-SH cells. However, phosphorylation of ERK1/2 and JNK MAPKs were achieved at 100 and 200 μg/ml of the extract.

CONCLUSIONS

Taken together, these results clearly demonstrate that Picralima nitida suppresses PGE2 production by targeting multiple pathways involving NF-κB and MAPK signalling in IL-1β-stimulated SK-N-SH neuronal cells.

Synthesis, pharmacological study and docking calculations of new benzo[f]coumarin derivatives as dual inhibitors of enzymatic systems involved in neurodegenerative diseases

Background: Due to the complex etiology of neurodegenerative diseases, there is growing interest in multitarget drugs. In this study we synthesized and evaluated a new series of compounds, with benzo[f]coumarin structure, as potential inhibitors of MAO-A, MAO-B, AChE and BuChE. Results: In vitro studies show that most of the studied compounds inhibited the activity of MAO-B in the nano- to micro-molar range. 3-(3´-methoxyphenyl)benzo[f]coumarin is the most active compound with an IC50 value against MAO-B of 2.44 nM. Most of the derivatives exhibited an important selectivity profile against the MAO-B isoform. Some of them also acted as in vitro inhibitors of BuChE, with 3-(2´-hydroxyphenyl)benzo[f]coumarin being the most active with an IC50 value of 1.13 µM. In addition, a theoretical study of the physicochemical properties of the new compounds, as well as a docking study in both MAO isoforms, were carried out. Important structure–activity relationships were obtained. Conclusion: Important preliminary structure–activity relationships were concluded from the experimental results. These results encourage us to further explore the potential of this chemical family as potential drug candidates for the treatment of Alzheimer‘s disease.

Hydrogen sulfide inhibits A2A adenosine receptor agonist induced β-amyloid production in SH-SY5Y neuroblastoma cells via a cAMP dependent pathway

Alzheimer's disease (AD) is the leading cause of senile dementia in today's society. Its debilitating symptoms are manifested by disturbances in many important brain functions, which are influenced by adenosine. Hence, adenosinergic system is considered as a potential therapeutic target in AD treatment. In the present study, we found that sodium hydrosulfide (NaHS, an H2S donor, 100 µM) attenuated HENECA (a selective A2A receptor agonist, 10-200 nM) induced β-amyloid (1-42) (Aβ42) production in SH-SY5Y cells. NaHS also interfered with HENECA-stimulated production and post-translational modification of amyloid precursor protein (APP) by inhibiting its maturation. Measurement of the C-terminal APP fragments generated from its enzymatic cleavage by β-site amyloid precursor protein cleaving enzyme 1 (BACE1) showed that NaHS did not have any significant effect on β-secretase activity. However, the direct measurements of HENECA-elevated γ-secretase activity and mRNA expressions of presenilins suggested that the suppression of Aβ42 production in NaHS pretreated cells was mediated by inhibiting γ-secretase. NaHS induced reductions were accompanied by similar decreases in intracellular cAMP levels and phosphorylation of cAMP responsive element binding protein (CREB). NaHS significantly reduced the elevated cAMP and Aβ42 production caused by forskolin (an adenylyl cyclase, AC agonist) alone or forskolin in combination with IBMX (a phosphodiesterase inhibitor), but had no effect on those caused by IBMX alone. Moreover, pretreatment with NaHS significantly attenuated HENECA-elevated AC activity and mRNA expressions of various AC isoforms. These data suggest that NaHS may preferentially suppress AC activity when it was stimulated. In conclusion, H2S attenuated HENECA induced Aβ42 production in SH-SY5Y neuroblastoma cells through inhibiting γ-secretase via a cAMP dependent pathway.

Chronic hypoxia induces the activation of the Wnt/β-catenin signaling pathway and stimulates hippocampal neurogenesis in wild-type and APPswe-PS1ΔE9 transgenic mice in vivo

Hypoxia modulates proliferation and differentiation of cultured embryonic and adult stem cells, an effect that includes β-catenin, a key component of the canonical Wnt signaling pathway. Here we studied the effect of mild hypoxia on the activity of the Wnt/β-catenin signaling pathway in the hippocampus of adult mice in vivo. The hypoxia-inducible transcription factor-1α (HIF-1α) was analyzed as a molecular control of the physiological hypoxic response. Exposure to chronic hypoxia (10% oxygen for 6–72 h) stimulated the activation of the Wnt/β-catenin signaling pathway. Because the Wnt/β-catenin pathway is a positive modulator of adult neurogenesis, we evaluated whether chronic hypoxia was able to stimulate neurogenesis in the subgranular zone (SGZ) of the hippocampal dentate gyrus. Results indicate that hypoxia increased cell proliferation and neurogenesis in adult wild-type mice as determined by Ki67 staining, Bromodeoxyuridine (BrdU) incorporation and double labeling with doublecortin (DCX). Chronic hypoxia also induced neurogenesis in a double transgenic APPswe-PS1ΔE9 mouse model of Alzheimer’s disease (AD), which shows decreased levels of neurogenesis in the SGZ. Our results show for the first time that exposure to hypoxia in vivo can induce the activation of the Wnt/β-catenin signaling cascade in the hippocampus, suggesting that mild hypoxia may have a therapeutic value in neurodegenerative disorders associated with altered Wnt signaling in the brain and also in pathological conditions in which hippocampal neurogenesis is impaired.

Brain stem hemorrhage due to cerebral amyloid angiopathy: the autopsy of a patient with Alzheimer's disease at a young age

We report findings from an autopsy of a male in his 40s who died of a brain stem hemorrhage associated with cerebral amyloid angiopathy (CAA), senile plaques (SPs) and neurofibrillary tangles (NFTs), which are histopathological changes associated with Alzheimer's disease (AD). Our immunohistochemical study demonstrated amyloid β (Aβ) deposition in the small cerebral arteries and SPs. Although hypertension (178/132 mmHg) was detected, the subject was not treated accordingly. CAA coupled with hypertension might have caused the intracerebral hemorrhage (ICH).

Nose to brain microemulsion-based drug delivery system of rivastigmine: formulation and ex-vivo characterization

Alzheimer's disease (AD) is a progressive neurodegenerative disorder leading to irreversible loss of neurons, cognition and formation of abnormal protein aggregates. Rivastigmine, a reversible cholinesterase inhibitor used for the treatment of AD, undergoes extensive first-pass metabolism, thus limiting its absolute bioavailability to only 36% after 3-mg dose. Due to extreme aqueous solubility, rivastigmine shows poor penetration and lesser concentration in the brain thus requiring frequent oral dosing. This investigation was aimed to formulate microemulsion (ME) and mucoadhesive microemulsions (MMEs) of rivastigmine for nose to brain delivery and to compare percentage drug diffused for both systems using in-vitro and ex-vivo study. Rivastigmine-loaded ME and MMEs were prepared by titration method and characterized for drug content, globule size distribution, zeta potential, pH, viscosity and nasal ciliotoxicity study. Rivastigmine-loaded ME system containing 8% w/w Capmul MCM EP, 44% w/w Labrasol:Transcutol-P (1:1) and 48% w/w distilled water was formulated, whereas 0.3% w/w chitosan (CH) and cetyl trimethyl ammonium bromide (as mucoadhesive agents) were used to formulate MMEs, respectively. ME and MMEs formulations were transparent with drug content, globule size and zeta potential in the range of 98.59% to 99.43%, 53.8 nm to 55.4 nm and -2.73 mV to 6.52 mV, respectively. MME containing 0.3% w/w CH followed Higuchi model (r(2) = 0.9773) and showed highest diffusion coefficient. It was free from nasal ciliotoxicity and stable for three months. However, the potential of developed CH-based MME for nose to brain delivery of rivastigmine can only be established after in-vivo and biodistribution study.

Iron levels in the human brain: a post-mortem study of anatomical region differences and age-related changes

The link between brain iron homeostasis and neurodegenerative disease has been the subject of extensive research. There is increasing evidence of iron accumulation during ageing, and altered iron levels in some specific brain regions in neurodegenerative disease patients have been reported. Using graphite furnace atomic absorption spectrometry after microwave-assisted acid digestion of the samples, iron levels were determined in 14 different areas of the human brain [frontal cortex, superior and middle temporal, caudate nucleus, putamen, globus pallidus, cingulated gyrus, hippocampus, inferior parietal lobule, visual cortex of the occipital lobe, midbrain, pons (locus coeruleus), medulla and cerebellum (dentate nucleus)] of n=42 adult individuals (71±12 years old, range: 53-101 years old) with no known history or evidence of neurodegenerative, neurological or psychiatric disorders. It was found that the iron distribution in the adult human brain is quite heterogeneous. The highest levels were found in the putamen (mean±SD, range: 855±295μg/g, 304-1628μg/g) and globus pallidus (739±390μg/g, 225-1870μg/g), and the lowest levels were observed in the pons (98±43μg/g, 11-253μg/g) and medulla (56±25μg/g, 13-115μg/g). Globally, iron levels proved to be age-related. The positive correlation between iron levels and age was most significant in the basal ganglia (caudate nucleus, putamen and globus pallidus). Compared with the age-matched control group, altered iron levels were observed in specific brain areas of one Parkinson's disease patient (the basal ganglia) and two Alzheimer's disease patients (the hippocampus).

Synthetic nucleic acids delivered by exosomes: a potential therapeutic for generelated metabolic brain diseases

Many brain diseases, including Alzheimer's disease, are associated with genetic abnormalities. The search for more effective therapeutic approaches involving nucleic acids like interfering RNA, antisense oligonucleotides and mRNA has drawn much attention in the development of alternatives to virus-based gene therapy. Potentially, nucleic acids could not only specifically down-regulate and degrade misfolded proteins, but also relieve protein deficiencies by directing the translation of functional proteins. However, clinical applications have been stalled by the lack of proper delivery systems. Exosomes are nano-scale extracellular vesicles secreted by nearly all somatic cells. Recent work has revealed that exosomes play special roles in intercellular communication via the horizontal transfer of various RNAs among cells. Recently, the use of exosomes for the delivery of therapeutic nucleic acids to targeted cells has been demonstrated to be a practical approach. Here, we briefly review the general properties of exosomes and introduce three therapeutic nucleic acids. Based upon comparison with other delivery methods, exosomes are proposed as an ideal nucleic acid delivery system for metabolic brain disease therapy.

Regional analysis of the magnetization transfer ratio of the brain in mild Alzheimer disease and amnestic mild cognitive impairment

BACKGROUND AND PURPOSE

Manually drawn VOI-based analysis shows a decrease in magnetization transfer ratio in the hippocampus of patients with Alzheimer disease. We investigated with whole-brain voxelwise analysis the regional changes of the magnetization transfer ratio in patients with mild Alzheimer disease and patients with amnestic mild cognitive impairment.

MATERIALS AND METHODS

Twenty patients with mild Alzheimer disease, 27 patients with amnestic mild cognitive impairment, and 30 healthy elderly control subjects were examined with high-resolution T1WI and 3-mm-thick magnetization transfer images. Whole-brain voxelwise analysis of magnetization transfer ratio maps was performed by use of Statistical Parametric Mapping 8 software and was supplemented by the analysis of the magnetization transfer ratio in FreeSurfer parcellation-derived VOIs.

RESULTS

Voxelwise analysis showed 2 clusters of significantly decreased magnetization transfer ratio in the left hippocampus and amygdala and in the left posterior mesial temporal cortex (fusiform gyrus) of patients with Alzheimer disease as compared with control subjects but no difference between patients with amnestic mild cognitive impairment and either patients with Alzheimer disease or control subjects. VOI analysis showed that the magnetization transfer ratio in the hippocampus and amygdala was significantly lower (bilaterally) in patients with Alzheimer disease when compared with control subjects (ANOVA with Bonferroni correction, at P < .05). Mean magnetization transfer ratio values in the hippocampus and amygdala in patients with amnestic mild cognitive impairment were between those of healthy control subjects and those of patients with mild Alzheimer disease. Support vector machine-based classification demonstrated improved classification performance after inclusion of magnetization transfer ratio-related features, especially between patients with Alzheimer disease versus healthy subjects.

CONCLUSIONS

Bilateral but asymmetric decrease of magnetization transfer ratio reflecting microstructural changes of the residual GM is present not only in the hippocampus but also in the amygdala in patients with mild Alzheimer disease.

Gender, age-related, and regional differences of the magnetization transfer ratio of the cortical and subcortical brain gray matter

PURPOSE

To explore gender, age-related, and regional differences of magnetization transfer ratio (MTR) of brain cortical and subcortical gray matter (GM).

MATERIALS AND METHODS

In all, 102 healthy subjects (51 women and 51 men; range 25-84 years) were examined with 3-mm thick MT images. We assessed MTR in automatically segmented GM structures including frontal, parietal-insular, temporal, and occipital cortex, caudate, pallidus and putamen, and cerebellar cortex. A general linear model analysis was conducted to ascertain the linear and quadratic relationship among the MTR and gender, age, and anatomical structure.

RESULTS

The effect of gender was borderline (P = 0.07) in all GM structures (with higher MTR values in men), whereas age showed a significant linear as well as quadratic effect in all cortical and subcortical GM structures (P ≤ 0.001). Quadratic age-related decrease in MTR began at about 40 years of age. Mean and standard deviation (SD) of MTR had the following decreasing order: thalamus (58.3 + 0.8), pallidus (56.8 ± 1.3), caudate (55.5 ± 1.6) and putamen (54.6 ± 1.1); temporal (56.8 ± 0.9), parietal-insular (56.8 ± 1.1), frontal (56.5 ± 1.1), occipital (55.4 ± 1.0) and cerebellar (53.2 ± 1.0) cortex. In post-hoc testing, all regional pairwise differences were statistically significant except pallidus vs. temporal or parietal-insular cortex, caudate vs. occipital cortex, frontal vs. parietal-insular or temporal cortex.

CONCLUSION

MTR of the cortical and subcortical brain GM structures decreases quadratically after midlife and shows significant regional differences.

Estimation of the long-term care needs of stroke patients by integrating functional disability and survival

Objectives

This study aimed to estimate the dynamic changes of different physical functional disabilities and life-time care needs for patients with stroke.

Data Sources and Study Design

We examined a hospital-based cohort including 16,043 patients who had their first stroke during 1995–2010. The Barthel Index (BI) was used to measure disability levels in 1,162 consecutive patients, with a total of 1,294 measurements at the stroke clinics and the rehabilitation wards, and a cross-sectional design.

Extraction Methods

The survival function was extrapolated to lifetime by a semi-parametric method and multiplied with proportions of different disabilities over time to obtain the long-term care needs for different stroke subtypes.

Principal Findings

On average, stroke patients would suffer at least 0.86 years with mild disability, 1.24 years with moderate disability and 1.39 years with severe disability, as measured by the BI. Among these, patients with a cardio-embolic infarct or intracerebral hemorrhage (ICH) suffered more than 2 years of severe disability. Assistance in bathing was the most common need for care in stroke patients.

Conclusions

Among different subtypes of stroke, cardio-embolic infarct and ICH lead to the longest durations of severe physical functional disability. The method presented in this work may also be applied to other chronic diseases and different functional disabilities.

Sirtuin deacetylases as therapeutic targets in the nervous system

Sirtuins are a conserved family of deacetylases whose activities are dependent on nicotinamide adenine dinucleotide (NAD+). Sirtuins act in different cellular compartments, such as the nucleus where they deacetylate histones and transcriptional factors, in the cytoplasm where they modulate cytoskeletal and signaling molecules, and in the mitochondria where they engage components of the metabolic machinery. Collectively, they tune metabolic processes to energy availability, and modulate stress responses, protein aggregation, inflammatory processes, and genome stability. As such, they have garnered much interest and have been widely studied in aging and age-related neurodegeneration. In this chapter, we review the identification of sirtuins and their biological targets. We focus on their biological mechanisms of action and how they might be regulated, including via NAD metabolism, transcriptional and posttranscriptional control, and as targets of pharmacological agents. Lastly, we highlight the numerous studies suggesting that sirtuins are efficacious therapeutic targets in neurodegenerative disease and injury.

Dysregulation of leptin signaling in Alzheimer disease: evidence for neuronal leptin resistance

Leptin signaling has received considerable attention in the Alzheimer disease (AD) field. Within the past decade, the peptide hormone has been demonstrated to attenuate tau hyperphosphorylation in neuronal cells and to be modulated by amyloid-β. Moreover, a role in neuroprotection and neurogenesis within the hippocampus has been shown in animal models. To further characterize the association between leptin signaling and vulnerable regions in AD, we assessed the profile of leptin and the leptin receptor in AD and control patients. We analyzed leptin levels in CSF, and the concentration and localization of leptin and leptin receptor in the hippocampus. Significant elevations in leptin levels in both CSF and hippocampal tissue of AD patients, compared with age-matched control cases, indicate a physiological up-regulation of leptin in AD. However, the level of leptin receptor mRNA decreased in AD brain and the leptin receptor protein was localized to neurofibrillary tangles, suggesting a severe discontinuity in the leptin signaling pathway. Collectively, our results suggest that leptin resistance in the hippocampus may play a role in the characteristic changes associated with the disease. These findings are the first to demonstrate such dysregulated leptin-signaling circuitry and provide novel insights into the possible role of aberrant leptin signaling in AD. In this study, increased leptin was found in CSF and hippocampus in Alzheimer disease indicating its physiological up-regulation, yet leptin receptor mRNA was decreased and leptin receptor protein was localized to neurofibrillary tangles, suggesting a discontinuity in the leptin signaling pathway. The lack of leptin signaling within degenerating neurons may represent a novel neuronal leptin resistance in Alzheimer disease.

Cessation of neoangiogenesis in Alzheimer's disease follows amyloid-beta immunization

Pathogenic neoangiogenesis in Alzheimer's disease (AD) is due to amyloid-beta (Aβ) and results in blood-brain barrier (BBB) leakiness in AD. It likely occurs as a compensatory response to impaired cerebral blood flow and provides a strong link between brain vascularity and AD. Aβ immunotherapy is an experimental treatment for AD; however, unexpected negative vascular side effects seen in early human clinical trials demonstrate that our knowledge of Aβ and AD pathogenesis is incomplete. We demonstrate that immunization with Aβ peptides neutralizes the amyloid trigger leading to neoangiogenesis and reverses hypervascularity in Tg2576 AD mice. This process resolves plaque burden suggesting that neoangiogenesis is a key mechanism underlying plaque formation. A meta-analysis demonstrated that hypervascular reversion in vaccinated Alzheimer's patients. This appears to be the first example of vascular reversion following any therapeutic intervention and supports the conclusion that modulation of neoangiogenesis may repair damage in the AD brain.

Activation of innate immunity by lysozyme fibrils is critically dependent on cross-β sheet structure

Inflammation occurs in many amyloidoses, but its underlying mechanisms remain enigmatic. Here we show that amyloid fibrils of human lysozyme, which are associated with severe systemic amyloidoses, induce the secretion of pro-inflammatory cytokines through activation of the NLRP3 (NLR, pyrin domain containing 3) inflammasome and the Toll-like receptor 2, two innate immune receptors that may be involved in immune responses associated to amyloidoses. More importantly, our data clearly suggest that the induction of inflammatory responses by amyloid fibrils is linked to their intrinsic structure, because the monomeric form and a non-fibrillar type of lysozyme aggregates are both unable to trigger cytokine secretion. These lysozyme species lack the so-called cross-β structure, a characteristic structural motif common to all amyloid fibrils irrespective of their origin. Since fibrils of other bacterial and endogenous proteins have been shown to trigger immunological responses, our observations suggest that the cross-β structural signature might be recognized as a generic danger signal by the immune system.

Aerobic exercise combined with antioxidative treatment does not counteract moderate- or mid-stage Alzheimer-like pathophysiology of APP/PS1 mice

AIMS

The present study evaluated the combined treatment effects of aerobic exercise and antioxidative stress on moderate-stage Alzheimer's disease (AD).

METHODS

Ten-month-old APP/PS1 mice were given antioxidative treatment with acetylcysteine, along with aerobic exercise for 6 weeks. Spatial learning and memory were tested using the Morris water maze, and β-amyloid (Aβ) plaque deposits in the forebrain were quantified by Thioflavin-S staining. Levels of soluble Aβ1-42, β-secretase enzyme, ү-secretase enzyme, oxidative and antioxidant stress markers nitrotyrosine and peroxiredoxin-1, glial markers glial fibrillary acidic protein and ionized calcium-binding adaptor molecule 1, and synaptic protein synaptophysin in the hippocampus were all measured by western blotting and/or immunohistochemistry.

RESULTS

APP/PS1 mice showed severe declines in spatial learning and memory compared with their wild-type littermates, which were not attenuated by aerobic exercise combined with antioxidative treatment. The pathologic analysis revealed that Aβ deposition and production, oxidative stress, glial inflammation, and synaptic loss were not mitigated in the brain of exercised APP/PS1 mice, compared with the sedentary APP/PS1 animals.

CONCLUSION

This study reveals that a combined treatment of aerobic exercise plus antioxidative stress does not counteract pathophysiology in the moderate- or mid-stages of AD.

An exploration of the potential mechanisms and translational potential of five medicinal plants for applications in Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia, and represents a vast worldwide socio-economic burden, and in the absence of a current cure, effective therapeutic strategies are still needed. Cholinergic and cerebral blood flow deficits, excessive levels of oxidative stress, neuroinflammation and glutamate excitatory mechanisms are all believed to contribute to the development and progression of the disease. Scoparia dulcis, Catharanthus roseus, Sesamum indicum, Erythrina senegalensis and Vigna unguiculata represent five plants that have been used as traditional medicines for the treatment of AD in certain cultures. Review of the scientific literature was conducted to explore the properties of these plants that might be beneficial and explain what would be perceived by many to be largely anecdotal evidence of their benefit. All plants were found to possess varying levels of anti-oxidant capability. Scoparia dulcis was also found to potentiate nerve growth factor-like effects upon cell lines. Catharanthus roseus appears to inhibit acetylcholinesterase with relatively high potency, while Sesamum indicum demonstrated the strongest antioxidant ability. Comparisons with currently used plant derived therapeutics illustrate how these plants may be likely to have some therapeutic benefits in AD. The evidence presented also highlights how appropriate dietary supplementation with some of these plants in various cultural settings might have effects analogous or complementary to the so-called protective Mediterranean diet. However, prior to embarking on making any formal recommendations to this end, further rigorous evaluation is needed to better elucidate the breadth and potential toxicological aspects of medicinal properties harboured by these plants. This would be vital to ensuring a more informed and safe delivery of preparations of these plants if they were to be considered as a form of dietary supplementation and where appropriate, how these might interact with more formally established therapies in relation to AD.

Mitochondrial DNA oxidative damage and repair in aging and Alzheimer's disease

SIGNIFICANCE

Mitochondria are fundamental to the life and proper functioning of cells. These organelles play a key role in energy production, in maintaining homeostatic levels of second messengers (e.g., reactive oxygen species and calcium), and in the coordination of apoptotic cell death. The role of mitochondria in aging and in pathophysiological processes is constantly being unraveled, and their involvement in neurodegenerative processes, such as Alzheimer's disease (AD), is very well known.

RECENT ADVANCES

A considerable amount of evidence points to oxidative damage to mitochondrial DNA (mtDNA) as a determinant event that occurs during aging, which may cause or potentiate mitochondrial dysfunction favoring neurodegenerative events. Concomitantly to reactive oxygen species production, an inefficient mitochondrial base excision repair (BER) machinery has also been pointed to favor the accumulation of oxidized bases in mtDNA during aging and AD progression.

CRITICAL ISSUES

The accumulation of oxidized mtDNA bases during aging increases the risk of sporadic AD, an event that is much less relevant in the familial forms of the disease. This aspect is critical for the interpretation of data arising from tissue of AD patients and animal models of AD, as the major part of animal models rely on mutations in genes associated with familial forms of the disease.

FUTURE DIRECTIONS

Further investigation is important to unveil the role of mtDNA and BER in aging brain and AD in order to design more effective preventive and therapeutic strategies.

Cerebral Amyloidal Angiopathy--a disease with implications for neurology and psychiatry

Cerebral Amyloidal Angiopathy (CAA), which occurs sporadically in most cases but can also occur hereditarily, belongs to the group amyloidoses and is characterized by the deposition and accumulation of beta-amyloid (Aβ) in smaller arterial vessels of the brain. The deposition of Aβ leads to degenerative changes in the cerebral vessel system (thickening of the vessel wall, microaneurysm, constriction of vascular lumen, dissection), which favour the development of the clinical symptomatology most often associated with CAA. Besides haemorrhages, cerebral ischaemia, transient neurological symptoms, leukoencephalopathy as well as cognitive decline and even dementia may appear in connection with CAA. A definite diagnosis of CAA can only be made on the basis of a pathological assessment, even though diagnostic findings of cerebral neuroimaging and clinical symptoms allow the diagnosis of a probable CAA. At present, no causal therapy options are available. Although CAA is placed within the range of neurological illnesses, psychiatric symptoms such as cognitive impairment, personality change or behavioural problems as well as depression are plausible clinical manifestations of CAA and may even dominate the clinical picture. Apart from epidemiological, pathogenetical, clinical and diagnostical aspects, possible psychiatric implications of CAA are discussed in the review article.

Decisive role of Reelin signaling during early stages of Alzheimer's disease

Alzheimer's disease (AD) is one of the largest unmet medical concerns of our society. Around 25 million patients worldwide together with their families are still waiting for an effective treatment. We have recently initiated a re-evaluation of our knowledge of the molecular and cellular mechanisms underlying sporadic AD. Based on the existing literature, we have proposed a mechanistic explanation of how the late-onset form of the disease may evolve on the cellular level. Here, we expand this hypothesis by addressing the pathophysiological changes underlying the early and almost invariant appearance of the neurofibrillary tangles, the only reliable correlate of the cognitive status, in distinct brain areas and their consistent "spread" along interconnected neurons as the disease advances. In this review we present and discuss novel evidence that the extracellular signaling protein Reelin, expressed along the olfactory and limbic pathways in the adult brain, might hold a key to understand the earliest steps of the disease, highlighting the olfactory pathway as the brain's Achilles heel involved in the initiation of the pathophysiological characteristic of late-onset AD.